


Saber Will Be Mine

by Boomerangfish2



Category: Fate/Grand Order, Fate/stay night & Related Fandoms, Fate/stay night (Visual Novel)
Genre: Absorption, F/F, Inspired by Fanart, Vore, there will be vore motherfucker
Language: English
Status: Completed
Published: 2019-04-23
Updated: 2019-05-05
Packaged: 2020-01-24 08:36:44
Rating: Explicit
Warnings: Graphic Depictions Of Violence, Major Character Death
Chapters: 3
Words: 6,923
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18567769
Author URL: https://archiveofourown.org/users/Boomerangfish2/pseuds/Boomerangfish2
Summary: Here's a story based on a comic by Mori (Mad Forest), an artist on Pixiv: https://www.pixiv.net/member_illust.php?mode=medium&illust_id=70076900. The designs of Medea were also inspired by REIA https://twitter.com/Reia9131In this story, Medea finds a way to turn the tables on the other servants in the Holy Grail war, in a way that no one could ever predict!TO CLARIFY: Marius, Saber's dragon familiar, is an original creation of Mori.I really enjoyed writing this and it meant a lot to me to know the original artists loved it! I hope you will as well!





	1. A New Power

**Author's Note:**

  * Inspired by [Medea Saga](https://archiveofourown.org/external_works/475633) by Mori (Mad Forest). 



Everything was starting to fall into place.  
Caster paced the room, eyeing the prize she had won: Saber. Saber, proud and chivalrous, had nonetheless fallen into her trap and was helpless before her.  
Saber was held in place by a fleshy mass constructed by Caster herself. Caster had found a magic book containing spells describing a Shoggoth, which could bring immense power to the user. The Shoggoth was manipulated by Caster and could go wherever she wished at will. It could turn into a small puddle or expand to the size of a human. Malleable and multi-purpose, it was doing a wonderful job containing the powerful Saber.  
“Caster. I know not what you intend. Release me now and I will destroy you quickly.”  
Caster laughed.  
“Saber, you aren’t in a position to enforce your demands. I suggest you hold your tongue.”  
Caster held Saber by the chin, drawing her lips ever closer. Caster made contact and thrust her tongue inside Saber’s mouth. She transferred some mana to the rowdy swordswoman like an electric tingle. Saber made a lewd noise.  
“You see?” Caster said as she broke the kiss. “There are rewards for doing as I say.”  
Saber struggled in the fleshy prison.  
“Caster, I swear that when I-“ Saber began, but as she began there was a loud crash through the side of the shrine where Caster was hiding out.  
In stepped one of the Masters, Rin Tohsaka, and her servant, Archer. Bringing up the rear was Marius, Saber’s dragon familiar she had raised from a child.  
“Saber! Are you alright?” Rin called.  
“Caster. You’ll pay for taking Saber from us.” Archer said as he drew his swords.  
Caster laughed again.  
“It matters not how many you are. I will take you all on!” Caster began to chant a spell, when Marius opened his mouth. The dragon ejected a spiky like tongue, skewering Caster instantly. As the tongue pierced Caster’s backside, spikes protruded from the main body, not unlike Lancer’s Gae Bolg.  
“Guh..!” Caster gasped as she crumpled to the floor. Wounds covered her body and her life poured onto the ground. Not even the level of mana she had consumed would help her regenerate these wounds.  
As Caster fell, the Shoggoth released Saber. She collapsed, muscles atrophied after being held in captivity for hours. She struggled to her feet and was assisted by Rin.  
“Saber! Are you alright?”  
Saber dusted herself off.  
“Yes, Rin. I’m doing just fine now, thanks to you. Caster’s Rule Breaker rendered me paralyzed, but with Caster’s energy fading, I think I’ll be fine.”  
Caster, meanwhile, felt her consciousness slipping away.  
“Damn this body… if it were not for my injuries I could continue this fight… Oh, Saber, you were so close to being mine…!”  
Caster tried to rise, and failed. Marius and Archer were comforting Saber along with Rin.  
Caster knew her time was running out. She knew she had to act fast.  
The Shoggoth, now a pile upon the floor, still moved at Caster’s command.  
Caster used her remaining magical energy to command it towards the group of four who had ruined her plans.  
The Shoggoth slipped and squirmed across the floor, a being of indeterminate mass, shrinking and expanding as it edged closer to the target.  
“We should get out of here.” Saber was saying.  
Archer and Marius walked forward and stood over Caster.  
“Your time is up, Caster.” Archer said.  
Caster could barely manage to speak.  
“Oh, Archer, if only that were the case.”  
“Return to the Throne of Heroes, Caster. I will dispatch you any time you appear.”  
Meanwhile, the Shoggoth approached Saber and was now within striking distance.  
“Marius, finish off Caster!” Archer called.  
The Shoggoth creeped up Saber’s leg. Saber was still oblivious.  
“I don’t think so!” Caster yelled as Marius unleashed a blast.  
In the blink of an eye, a shield surrounded Caster and protected her from the dragon’s beam.  
The shield dissipated shortly after the dragon’s attack was exhausted.  
The Shoggoth was now taller than Saber. Rin gasped as she looked behind Saber.  
Caster raised her head to see her plan completed.  
“Saber! You are all mine! Shoggoth, engulf!”  
As the Shoggoth expanded to reveal a secondary layer of red flesh, Rin shouted out.  
“Saber!”  
Too late, Saber turned.  
“What is it?”  
The Shoggoth curled like a tidal wave and covered Saber from head to toe. The fleshy being was doing its best to make sure Saber could not escape.  
Caster laughed, as Rin cried out for Saber.  
“Fools! It is already too late!”  
Saber’s muffled cries could be heard as the Shoggoth moved to consume her. The flesh would stretch back to reveal Saber still struggling, but only to be covered up once again by the expanding Shoggoth. It was a hopeless battle as Saber sank deeper and deeper into the flesh of the creature.  
Caster, emboldened by her success, rose to her feet and approached the organism.  
“Fufufu… yes, the tome I read about this being was well worth it. The Shoggoth is an ancient creature of great power! Not only that, but by bonding with this creature, I can bend it to my every whim. Saber, watching you struggle within gives me great pleasure.”  
Archer stepped forward.  
“Caster!”  
Caster waved her arm and magical aura pushed him back.  
“Back, you fool!”  
As Archer regained his footing, he noticed Caster threw up an even bigger shield than before, covering her and the Shoggoth- and thus, Saber along with it.  
“Caster must’ve had more mana remaining than we thought!” he yelled to his master.  
Meanwhile, Saber continued her desperate fight. When a limb of hers was freed, the Shoggoth would expand to take it back into the fold.  
The fleshy prison began to bind her inside, when Saber had an idea.  
“I need my armor!” Saber said. Instantly, her armored dress materialized, but the heavier weight made it harder to move in the Shoggoth. Tentacles sprouted from the hot fleshy walls as Saber tried to move. As Saber was enwreathed by the tentacles, she saw her armor disappear!  
“My mana is being drained!” Saber cried in anguish.  
The fleshy Shoggoth was closing around Saber, forcing her into a smaller and smaller space. The red inner flesh had Saber completely wrapped up, and she felt her consciousness slipping away.  
On the outside, the Shoggoth made tightening noises as it compacted itself. Saber endured the squeezing as best as she could.  
“Fufufu… now time to show you what the Shoggoth can do.” Caster announced. She curled a finger towards her, and the Shoggoth shot into the air.  
“Saber, no!” Rin called. It was too late. The Shoggoth splashed onto Caster’s dress near her stomach, as Caster waited with arms wide open.  
Caster grabbed the mass attached to her midsection and brought it close as she cooed,  
“Okay, Saber. Now the fun part begins.”  
Saber heard Caster’s laughter as she felt herself becoming one with Caster’s body. She was shrinking and being made to modify Caster’s spirit origin. Saber’s hands were imprisoned behind her by flesh as her knees came up to her chin as she was slowly made to crouch inside Caster’s stomach.  
Caster used her cape to cover her transformation. She laughed the entire time Saber’s mana flowed into her.  
Saber’s vision was limited, but she could definitely feel Caster’s magic circuits running over her body, using her as a magical battery of sorts. She could also hear Caster chanting to complete the ritual the Shoggoth had started.  
“I’m inside Caster?? How can this be?” wondered Saber aloud.  
“Hoho, cease your struggles Saber, and become part of my being.” Caster called to her. Saber felt herself being imprisoned in a meat cocoon, unable to move, and trapped in a ball of flesh deep inside Caster.  
“Rin… I’m sorry.” Saber said as she then hung her head low. The flesh covered her completely and magic circuits glowing blue lit up her sleeping face.  
“Now, Saber, you are mine. Let us become one.” Caster said.  
The Shoggoth inside Caster connected Saber’s appendages to her own, causing them to fuse together. Caster began to call on the mana reserve and abilities of Saber inside her.  
Saber’s armor appeared over Caster’s dress, as her sleeves began to grow larger to match Saber’s. The legendary sword Excalibur began to materialize in Caster’s hand. Caster’s Rule Breaker blade grew from the hilt, running the entire length of the sword in a jagged fashion like the original blade. Caster’s cape hood shrank and grew fur trim around the neck, as Saber’s regal cape was. A golden charm held the ends of the cape together at Caster’s neck. As the hood disappeared, Caster’s braids unfurled and her hair grew longer, and changed to a blonde on top, blue on bottom gradient.  
“Ah… it’s finally complete. Archer, how do you like my transformation?”  
Mana energy was pouring out of Caster’s new form. Despite the power boost, she knew this form with Saber was temporary at best. She needed to defeat Archer and Marius, and quickly.  
Then, when she knew she was alone, she would complete her fusion with Saber.  
Archer sprang forward, and Caster readied Excalibur. With her new heightened speed, Caster ducked under Archer, and cut upwards with Excalibur, piercing Archer’s chest and slicing him in half. Archer’s top half fell to the floor, while his torso collapsed on Caster’s other side.  
Rin was momentarily stunned.  
“ARCHER?!?”  
Marius, detecting Rin’s hesitation and the new danger, grabbed Rin by the scruff of her sweater. With his great wings, he flapped into the night sky, leaving Caster and the wreckage of the temple behind.  
“ARCHER!!!!!!!!!!!!!!” Rin called as they fled into the night sky.  
“Fufufu. This Holy Grail War will be mine after all.” Caster laughed to herself.

 

Outside in the woods, Archer collected himself. His afterimage had been totally shredded by Caster.  
“I’m glad I didn’t underestimate her. With the power of Saber, she’s almost unstoppable now.”  
With his Independent Action, he could operate out of range of Rin for a while. He then made his way stealthily through Caster’s woods towards the Tohsaka manor, hoping the disorientation of her new body would prevent Caster from honing in on his energy.

 

Caster was studying her new, changed body.  
Saber’s power was running through her. Caster was totally flush with the influx of mana and strength inside her now.  
“This turned out better than I could’ve hoped for.”  
Caster held out her free hand, examining the gauntlet on her hand, stolen from Saber.  
“Now that I have a moment, I can focus on integrating Saber more into my spirit origin. I’m sure this form is temporary and won’t last forever.”  
Saber’s voice entered Caster’s mind.  
“What dark magic is this? I will not be your slave!”  
Caster chuckled.  
“I told you, it’s a Shoggoth. An ancient beast, amorphous and able to take any shape. As for being my slave, Saber, as much as I want that, you will not be my slave.”  
“Then release me this instant!” Saber yelled inside of Caster’s mind.  
“You will not be my slave, but you will be a part of me. We’re going to be working very closely together from here on out. Hahaha!”  
Saber cried out in anguish, but knew that there was nothing she could ultimately do, a prisoner inside of Caster.  
Caster laughed to herself as she checked the magical barrier around her shrine. The area seemed to be clear, for now. She set up more wards in the woods to protect against intruders, and then set about her work.  
“It’s been a pleasure speaking with you, Saber. However, I’m going to make that power of yours mine forever now.” Caster said, and she began concentrating on Saber inside her.  
“What is going on?!” Saber asked.  
Caster looked at Saber in her mind’s eye, a welcome guest in her body.  
“To put it crudely, I am digesting you. Your body will meld with mine completely, rendering us one being instead of two. You have lost your abilities, your body, and now you will give your mind to me as well. There will be no trace of you remaining.”  
Saber was powerless to resist as Caster fused with Saber for good. Caster, in her private room, dismissed her armor and began undressing.  
“Goodbye now, Saber.”  
Caster sped up her digestion process, and Saber’s consciousness disappeared from her mind entirely. The two were now completely one.  
As Saber faded away forever, Caster’s bust size increased a bit. The King of Knights was not the most endowed, but every bit helped Caster. Caster looked at her naked body and examined it in the moonlight coming through the doors. Her body had remained largely the same, aside from inheriting more breast mass. She looked at her face in a mirror she created with magecraft- one could tell that she had inherited some of Saber’s facial features. Her face was still largely her own, however. As unconventional as it was, she also liked her blonde and blue hair. Her signature braids had unfurled during the process. Caster’s hair gained the trademark ahoge that Saber had. Caster was glad about snagging this cute feature of Saber’s.  
Caster felt a wave of excitement rush over her. This new body was powerful, and there was no telling the limits of her power now. Even if she lost the Grail War, Caster was delighted over what she had accomplished. Fusing with Saber completely also meant the King of Knights was likely removed from the Throne of Heroes entirely, and Caster would likely use this body for all future Grail Wars.  
“I believe I will walk among the town. I want to show everyone my new appearance. In the mean time, I may learn more about my enemies.”  
Caster conjured up a purple high neck sleeveless dress, the color of her robes. It accentuated her new cleavage, with a hole cut below for style. The area between her collar and breasts was bare, except for the straps that connected the bra to the high neck piece. Underneath the neck piece, sitting above her cleavage rest the golden jewelry that connected her cape together. She also pulled on tight black thighs and gloves to go with her new dress.  
Caster loved the feel of the dress. Surely people would notice when she went out to investigate. Caster wanted them to look. She wanted the whole world to look upon her in awe.  
There was a powerful new Servant in town with her eyes on the Holy Grail.  
Caster left the shrine behind and descended the mountain for Fuyuki.


	2. Mediatria's Wrath

**Summary for the Chapter:**

> Here's a story based on a comic by Mori (Mad Forest), an artist on Pixiv: https://www.pixiv.net/member_illust.php?mode=medium&illust_id=70076900. The designs of Medea were also inspired by REIA https://twitter.com/Reia9131
> 
> In this chapter, Medea tracks down Rin and Shirou to take the fight to them. Rin and Shirou have to find some way to defeat Medea before she grows more powerful!
> 
> This one is a little shorter than the other two, but I'm excited to post the last one!

Caster had finally tracked down Archer and his Master. They were hiding in a large house alongside Saber’s former Master.  
“Poor boy. He is a no-talent magus who lost his Servant to one who was better suited to use her abilities.” Caster said to herself as she plotted her attack outside the home.   
Caster used her new agility gained from Saber to leap onto the top of the house. Activating Saber’s armor, she used Excalibur to cut an entrance hole right in the roof, to the surprise of the occupants inside.  
Caster came crashing down right in the middle of their meal.  
“What in the hell?”  
Rin, Shirou and Sakura were all dumbfounded as Caster appeared right before their very eyes.   
“Caster?! How did you find us here?” the boy asked her.  
“Fufu. Ah, Emiya Shirou. I simply used your servant’s memories, which are now mine. Saber knew exactly where your house was and all I had to do was follow her trail.”  
Caster stepped off the dining room table, her plated boots from Saber crunching it under every step.   
“Shirou! Run! I’ll hold off Caster!” Rin said, and Archer appeared behind her.  
“And leave you? No!” Shirou shouted- brave, but reckless. Caster chuckled.  
“You don’t have a Servant, you can’t engage her! You’ll be killed!”  
“Just because you’re correct doesn’t mean that you’re right!” Shirou retorted.  
Archer looked at the boy harshly.   
“This is no time for your useless ideals, Shirou. Run!”  
Caster was tired of waiting. She ran at Archer with Excalibur, colliding with his twin blades. The kitchen suffered more damage as the two powerful servants fought.  
“Sakura! Sakura!” Shirou called, but she was nowhere to be seen. He ran out the door. Caster decided to let him go- after all, he was just one boy. Her real enemy was in front of her.  
“Archer! Let Caster have it!”   
Archer was doing his best, but Caster was powerful now with Saber’s strength. Excalibur was not to be defeated by the twin blades Archer wielded. Caster used a wave of magic with Excalibur and destroyed a wall of the Emiya household. Archer and Caster clashed blades until they were out in the courtyard.  
“That illusion trick was impressive before, Archer. But this time, I won’t let you escape. You are mine.” Caster told the stoic Servant.  
“Don’t worry. I’m not running away this time.”  
Caster then heard a voice call out-  
“RIDER!”  
A black boot shot out of the air and kicked Caster in the stomach. Then, Caster was bound with chains, dropping her holy sword. A long-haired woman with a blindfold had caught her, and Archer held the blade to Caster’s neck.  
“Give the order, Master.”  
Caster was in shock as she saw the purple haired girl from before approach with a Command Seal on her hand. So this was Rider’s Master?  
“This is it, Caster. You shouldn’t have come around here.” Rin said as she appeared behind Archer.  
Caster began to laugh.  
“Do you fools think all I inherited from Saber was her sword? I can also do this!”  
Caster used Saber’s Mana Burst, increasing her strength dramatically, allowing for Rider’s chains to be broken. She regained Excalibur and then jumped to the top of the Emiya household.   
“I’ll take you both on!”  
Archer, Rider and Caster’s fight resumed. Caster was able to keep up with the both of them, much to her own surprise. One on one combat was not her style, and two on one would’ve been a death sentence before absorbing Saber. But now that she had her strength, she could-  
“Gah!!”  
She miscalculated.  
Archer’s sword swing met her unprotected arm, cutting it off. It fell to the street below.   
“No! No!” Caster yelled as she saw her own wound.  
Archer and Rider once again had the advantage.  
If that wasn’t bad enough, the noise Caster heard made her even more afraid.  
“ROARRRRRR!!!”  
The large man came into view, carrying his small Master and Shirou from earlier.  
“Let us down, Berserker!” The tiny Master commanded. Berserker obliged and drew his sword of stone, with wicked jagged edges.  
“Little brother told me he was in trouble and to come straight away! Don’t worry little brother, your big sister is going to clean up this mess for you!”  
Caster was surrounded, one arm down and outnumbered by 7, counting the human Masters.   
That did not mean that she was defeated, but it did make her options more interesting.  
“I see. So I had to have 3 servants arrive to defeat me? Marvelous.”  
As Caster spoke, she reached out in her mind’s eye to her arm on the street. As a side effect of the shoggoth manipulation and Saber absorption, her whole body became malleable with a skill called Self-Modification EX. Her arm converted to shoggoth sludge, and made its way down the street to the group of 3.   
“Caster, this is no time for words. Surrender, or die.” Archer said.  
“Archer, you are a simple-minded fool if you believe those to be my only options.” Caster said confidently. Caster had to stall for more time, and picking at the prideful Archer seemed a good bet.  
Sakura and Rin had made their way to the roof of the Emiya household, safely behind their servants.  
Underneath Caster’s dress, another shoggoth sludge was forming. It was building behind her back, hidden by Saber’s cape.   
“Berserker! Destroy Caster!” Shirou’s big sister called.  
“This battle is still mine-and so are you!”  
Caster’s sludge sprang into action.  
The sludge on her back tore through her clothes, forming a tail hovering over her head. She plopped the tail mouth down around Rider’s head, encapsulating her and forcing her to stand still.  
“Archer, look!”  
Archer saw what Rin was pointing to- Berserker was struggling against sludge of his own. The shoggoth was covering the giant’s limbs even as he roared with defiance.  
“Haha! Even the mighty berserker cannot fight the shoggoth!”  
Caster’s tail sucked away at Rider, taking her inside the tail with powerful grip. Rider’s hands dropped her chain as her arms disappeared inside Caster’s tail.  
“I won’t let this happen again!” Archer called, but Caster used a magic blast to rocket him off the roof. She saw him crash into another building. Satisfied, she turned her attention to the magnificent female form entering her now.  
Rider was quickly becoming nothing more than a bulge in her shoggoth tail. The long black leather boots disappeared into the maw of the tail, and Caster felt Rider move down her insides. Caster smiled as she relished the thought of more power coming to her.  
Berserker was not having an easy time escaping the shoggoth. The titan was being wrapped up slowly, and now only his defiant eye shined out as his strength fled him. With another stretch over the exposure, the mighty Servant was covered up completely. The shoggoth sludge began to compact him with audible struggling into a more absorbable form.  
Caster watched with glee. She had no desire for any of Berserker’s traits- rather it was his raw power that she sought. She made sure to make his contribution to her physical form as minimal as possible.  
Rider’s body entered Caster’s backside through the tail, and the tail returned inside of Caster to help make the absorbing process easier. Caster then used her finger to command the Berserker sludge to come back to her. The sludge had grown so large that it covered her completely as she began to change.  
Rider was stored in the same temporary spot as Saber was earlier, along with Berserker. Caster’s appearance did not change too much- her plated boots grew to knee length to emulate Rider’s, and her chest size increased a bit. Though there were no physical changes from him, Berserker’s strength flooded her, bringing her immense power and raw destruction.   
A satisfied sigh escaped Caster’s lips as her new victims found their place inside her body.  
As she opened her eyes, the Masters were already fleeing, running from her. Caster began to laugh. She raised her foot and stomped. With her new Berserker class strength, her plated boots crashed through the roof and brought the house down around her. She reveled in the destruction, and when she had enough, there was little left for anyone to inhabit.   
Caster made her way back to the shrine to digest her adversaries. She would let them return to the Throne of Heroes, however- it was Saber that Caster wanted to keep forever.  
Caster dismissed her armor and threw her hood over her head. Saber’s former cape flowed behind her as she headed towards the mountain, leaving the burning Emiya household in her wake.


	3. Mediatria's Victory

**Summary for the Chapter:**

> Here's a story based on a comic by Mori (Mad Forest), an artist on Pixiv: https://www.pixiv.net/member_illust.php?mode=medium&illust_id=70076900. The designs of Medea were also inspired by REIA https://twitter.com/Reia9131
> 
> In this chapter, Mediatria edges ever closer to the Holy Grail and total victory. Will Shirou and the girls be enough to stop her?

They had finally stopped running when they made it to the Einzbern mansion.  
Shirou, Rin, Sakura and Illya couldn't think of anywhere else to go.  
Shirou spoke up first.  
"How are we going to defeat Caster now?"  
"We have Archer, but he needs rest after the beating he just got. It'll be a while before I can have him materialize." said Rin.  
Sakura was still in shock.  
"I can't believe she ate Rider..."  
Shirou comforted Sakura with a reassuring hand on her shoulder.  
"We'll get Rider back. We'll get Saber and Berserker back, too."  
"But how will we do that, little brother? I don't think there's a way to defeat Caster with just Archer." Illya told him.  
Shirou started to think. Rin was already on it as well.  
"We defeated Assassin... Caster absorbed Saber, Rider and Berserker... that means the only other servant left is..."  
Shirou saw a flash of the red spear from the Gaelic servant in his mind's eye.  
"Lancer!"  
"He's... not exactly our ally, Shirou. We also don't know who his master is."   
Shirou was shaking his head.  
"Believe me, if we had any other choice, I would take it. But he's the only other servant around. Maybe he can use that spear to impale Caster and then Archer can finish her off."  
"But how will we find him?" lllya asked.  
"We could always go to Father Kotomine and ask him if he knows. Also, if any of you want to step out now, that would be your chance." Rin told the others.  
Sakura shook her head.  
"No. I'm in until the end with Senpai."  
"Same here!" Illya chirped.  
"Alright. We're going to the church." Shirou said, and the four of them got ready.  
"Leysritt! Sella! We're leaving!" Illya called to her maids.  
The maids led the four out of the mansion and they made their way to Kotomine church in desperate hope of a plan to defeat Caster once and for all.

Caster was reveling in her victory.   
Not even the arrogant King of Heroes was any match for her!  
Currently, the so-called King was coughing up blood as he knelt in defeat in front of Fuyuki Church.  
"Gnnn... mongrel! You dare do this to me?"  
Caster chuckled. Excalibur was in her hand, ready to deal the final blow to Gilgamesh at any time.   
"King of Heroes, this power was not my own at first, but I have made great use of it, don't you think?"  
Gilgamesh spit blood at her feet.  
"You're a bastard mage. I won't let myself die here."  
Gilgamesh stood, and drew his sword, Ea.   
"I don't pull this out for just anyone."  
As Gilgamesh struggled to laugh, Caster went ahead and used her own Noble Phantasm.  
"Nine Lives Excalibur!"  
Gilgamesh's eyes widened. Caster's blows came hard and fast, shredding Gilgamesh's armor and his flesh. He had never felt pain like this in his long life.  
Caster pulled Excalibur behind her head, and Gilgamesh, from the previous War, knew what was coming next.  
"You bore me, King of Heroes. Excalibur!"  
The sword collided with the ground, unleashing the wave of holy energy the weapon was famous for. Gilgamesh scarcely had time for thought as he was incinerated and returned to the Throne.   
Father Kotomine, Gilgamesh's master, watched in horror as his own life ended by the holy blade's shockwave, and Kotomine Church was utterly destroyed. Unbeknownst to her, Caster had defeated the evil priest's ambitions, and ended the suffering for the many confined below the church.   
Caster caught her breath, flicking her hair behind her. She admired the blond locks on her gloves as she reached for her hair.  
"I did not expect to fight Gilgamesh, but I see now that I was more than capable for the job."  
Caster placed her free hand on her stomach.  
"It's all thanks to you, Saber. I hope you're happy in there. Absorbing you has been the highlight of the past few thousand years."  
Caster laughed, and patted her stomach. She knew Saber was completely integrated with her, but she felt as if she could still hear her voice.  
"Yes... mine forever. I don't even need the Holy Grail now. I was able to make my own greatest wish come true."  
Caster looked at the ruins of Fuyuki Church. Humans would surely be coming to investigate the massive damage here soon, but she had some time before that happened. The crater caused by Saber's... no, her holy sword was on a giant scale. She had never thought this level of power would be possible.  
Caster turned towards the hill, where Saber's master and the others were gathered.   
"Ah, you've come and saved me the trouble of hunting you down. Thank you."  
Shirou cried out, "Caster! What have you done?"  
Caster gestured towards the church.  
"Isn't it obvious? I destroyed Kotomine and his Servant. You didn't know it, but he had a servant of his own, another Archer like yours. I didn't absorb him, but I did turn him to ash."  
Rin looked towards Shirou.   
"Shirou! Let's get out of here!"  
Shirou was already running towards Caster.  
"Get out of here, Rin! I'll hold off Caster!"  
Caster smiled.  
"Foolish boy. There's no defeating me."  
"Give me back SABER!!!!" Shirou said, as he prepared a punch.   
Caster caught Shirou's head with her arm, and slammed him into the ground. Rin and the others gasped audibly.   
"Stay in your place, boy. There's no place for you in a match with me."  
"Archer!" Rin called out.  
The red servant collided with Caster from the side and brought her to the ground. Caster raised Excalibur and parried the double swords swinging at her.  
"Take Shirou and go!" Archer called.   
Sakura ran forward, but Caster wasn't about to let her take Shirou.  
Caster kicked Archer and forced him off of her as she righted herself.   
Caster raised Excalibur, but stopped as she felt an impact in her chest. As she looked down, she saw an arrow projecting from her stomach.   
Archer had regained his footing, and began pelting her with arrows. Under the cover of the arrows, Sakura took Shirou away.   
Rin came up closer to the battle scene.   
"Yes! Way to go, Archer!"  
It took a moment for Caster to deflect one of the arrows, and then she projected a magic forcefield, repelling the arrows and knocking back the Masters and Archer.  
Caster laughed as she removed and broke the arrows embedded in her. Thankfully, Saber's armor protected her from most of them.  
"Do you have any more tricks, Archer? I'm getting bored."  
Even across the great distance, she saw Archer's smile.  
"Actually, yes."  
Caster was amazed as the landscape around her changed. What was once the darkened brick walkway to the Kotomine church changed to a desert plain. Swords endlessly covered the plain for miles around, each one unique. Large cogs rotated endlessly in the sunset colored sky, like a Salvador Dali painting.  
"Is this... a reality marble? How are you capable of this kind of magic?" Caster called out to him.  
Archer smirked, and began to speak.  
"I am the bone of my sword,  
steel is my body and fire is my blood.  
I have created over a thousand blades  
Unknown to death,  
nor known to life.  
Have withstood pain to create many weapons  
Yet, those hands will never hold anything.  
So, as I pray-"  
Caster's eyes widened as she noticed she was surrounded with swords hovering in the air.  
"Unlimited Blade Works."  
An indescribable pain filled Caster as she was skewered with blades from all directions. For what could've only been a minute, but felt like eternity, Caster suffered the worst pain short of dying.  
Caster crumpled to the ground, searching for a way out of this fight. Even with Berserker's power, was she really this weak?  
Archer called out to Sakura.  
"Is Shirou okay?"  
Sakura gave Shirou a look over. His body was injured, but it seemed like he was still breathing.  
"I don't understand. With that level of injury, Sempai should've been killed!"  
Archer shook his head.  
"Give him time. He'll be just fine."  
Caster, meanwhile, was formulating her plan.  
She remembered that Berserker's legend included his remarkable recovery ability, similar to Shirou's own recovery right now. Shirou had no way of knowing, but thanks to absorbing Saber, Caster knew that Shirou had Excalibur's sheath inside of him, granting regenerative abilities beyond that of a normal human.  
Caster called on the Shoggoth on her back, sending it out towards the Masters.   
"I need more power... more..."  
Caster called upon Berserker's regeneration. Caster then had another lovely idea- with Berserker's Guts ability and Saber's mana burst, she would cause the regeneration to be almost instant and then use the remaining energy as physical strength.  
Caster smiled as the power rushed through her. Calling upon Saber as her core, she channeled the energy and with astonishing stamina and speed, she pushed off of the brick walkway and jumped into the air.  
"What the hell?!" Archer called out.  
As she fell to the ground, she aimed for Archer, striking him with brutal force.  
Archer, already fatigued from launching his Noble Phantasm, was pinned beneath Caster's powerful arms.  
"I won't end you this way, Archer. For your continued defiance, I have something worse in mind." Caster told him.  
"Nnng... What are you plotting?"  
Caster smiled and turned to Rin and the others.  
"Let's watch and see."  
The Shoggoth unfurled itself, growing from a tiny slime to a person-sized wave. Rin never took her eyes off Caster and Archer, and didn't know she was doomed until the shoggoth covered her.  
"Rin! No!" Sakura called out.  
Sakura left Shirou's side, and went to grab Rin's hand.   
"Sakura! Don't do it!"  
But it was too late, Caster made sure of that.  
"A two for one deal! I hadn't expected this, but I'll take it."  
The shoggoth engulfed Sakura's arms that reached out to Rin, and brought her closer to the malleable mass.  
Rin struggled vainly, uncovering her eyes and torso briefly before being covered again. Sakura's feet sank into the Shoggoth, making escape impossible as she was forced into the same tiny space with Rin.   
Caster turned to Archer.  
"You see, Archer, I wanted to absorb Rin and take her mana so that I could continue to exist and you would disappear slowly from this world. But, having two mages worth of mana doesn't sound bad at all!"  
Caster stood up, and Archer struggled to move.   
"Rule Breaker!"  
Caster stabbed Archer's hand, pinning him to the ground. He could not escape now without tearing off his own arm.  
Rin's struggles were ceasing. Sakura was almost subdued, as the Shoggoth covered her beautiful purple hair and her face disappeared. The shoggoth compacted them, bringing the two magi closer together inside of its infinite space.  
Caster laughed, and raised her hands to embrace the Shoggoth.  
"Come to me!"   
The shoggoth leapt from the ground, Illya screamed, and Caster was covered completely. She reveled in the transformation, absorbing the two girls and adding their mana to her own ample reserves.  
Caster's voice struggled to exit her now gelatinous form, but eventually her laughing became audible as her body regained its form.  
Meanwhile, Archer knew what he had to do. With all his might, he severed his own arm, got up, and made his way to Shirou.  
Bleeding out and fading fast, Archer spoke quickly.  
"Shirou. Don't forget the command seals. Only you can defeat Caster now. I'm sorry."  
Shirou, barely awake, still registered Archer's words clear as a bell.  
"Yes... Archer."  
Archer turned to the sun, which was starting to dawn behind the ruins of the church. His body became more transparent as he faded away, back to the Throne of Heroes.  
Caster, meanwhile, was completing her transformation.  
Caster's bodice now resembled Rin's shirt, with Saber's armor underneath. Her skirt shortened a little and became black to resemble Rin's. Rin's black hair now dominated the top of Caster's hair, then Saber's blonde, and finally Caster's own blue hair cascaded down her back. Rin and Sakura's ribbons, one on each side, tied off Caster's hair into Rin's trademark twintails. Sakura's contribution went directly to Caster's chest, increasing her bust size dramatically- but thankfully her clothes held to her new shape.  
"Hahaha! With the mana of two masters and the power of four Servants, I'm unstoppable! Unbeatable! There's no way you can stop me now, boy!" Caster laughed as Shirou struggled to stand.  
Shirou's body was in better shape than it was a moment before, but that was honestly not a big improvement.  
"Damn... is there really nothing I can do?"   
Caster slashed with Excalibur, making a gust that threatened to knock Shirou over.  
"Face it, boy. You fought me and you lost. Your servant, your friend's servants, and even your friends are part of me now."  
Shirou looked at Illya standing behind him.  
"Illya. I want you to run away and don't look back."  
"Don't be so foolish, little brother! Big sisters are supposed to protect their little brothers!"  
Shirou hugged Illya with his injured arm and prepared for the inevitable.  
Caster was taking a step forward when she was impaled by a red spear from the back. She cried out in agony as a blue blur appeared.  
Lancer, Shirou's nemesis, jumped on Caster's back and kicked off to free the spear from her flesh. Caster roared in pain and swung with Excalibur.   
"You worm! I was going to deal with you after the boy!" she cried.  
"Oh yeah? Well, you'll deal with me now." Lancer said.   
He then turned to Shirou as he squared up with Caster.  
"You better think of something quick! I don't know how long I can fight her!"  
Shirou's mind started working. What could they do now that everyone was gone? In the distance, Lancer and Caster traded blows with one another.  
"I don't know what I can do... but I need to try!"   
Shirou edged closer to the fight, as fast as he could. Illya supported him with her shoulder, tiny as she was.  
"Thank you, Illya."  
Caster slashed up at Lancer with a blow that he barely dodged. His spear was moving as fast as possible, but she seemed too strong for just him alone.  
Caster landed a lucky blow, and sank Excalibur deep into Lancer's shoulder.   
"Haha! Even the legendary knight of Ulster can't defeat me!"  
Lancer just smirked.   
"Tch. Why do I always have the worst luck with women?"  
With his own hand, he removed Excalibur from his shoulder.  
"I wish I could meet one someday that didn't try to kill me."  
Caster and Lancer resumed their fight, Lancer simply refusing to die from sheer stubborness.   
Shirou was thinking to himself.  
"Archer said... remember the Command spells... could I use one on Lancer? No, that wouldn't work..."  
Shirou then realized what he could do.  
He made his way forward, determined, never stopping. Breathing made his lungs feel like they were on fire, and his legs had shooting pain every time he took a step.  
But he kept on going.  
Closer and closer to Caster he came.  
Caster slashed Lancer in the gut, cutting him in half. Lancer's torso collapsed on the ground. With his legs separated from his chest and a deep wound in his shoulder, the brave warrior was finally at his end.  
"Tch... what a waste... I was looking forward to winning this time too..."  
Lancer disappeared, leaving behind no trace of the proud Ulster warrior.  
Caster turned to Shirou once more.  
"We can no longer delay, boy. You are out of surprises. Your head is mine."  
Shirou braced himself.  
"You may have absorbed Saber, but that means she's still inside you. You're one and the same."  
Caster looked at him inquisitively.  
"What are you getting at? If you want her back, I'm afraid it's too late."  
Shirou's command spells started to glow.  
"Caster... end this madness and become my wife!"  
The command spells worked their magic. Inside Caster's head, her desire to be a good wife and Saber's longing to be with Shirou were merging into a powerful force. Also inside Caster were Rin and Sakura's feelings towards him, resulting in a volatile cocktail of affection towards Shirou augmented by magic.  
"No! It cannot be...! I'm-"  
Caster dropped Excalibur and sank to the ground.  
Shirou held his breath. It was, without a doubt, the strangest idea he had ever had, but he knew nothing else.  
Caster looked at up at him, and the look in her eyes was vastly different now.  
"As you wish... Shirou."  
Shirou breathed a sigh of relief.  
"Okay, Caster. Let's go ho-"  
Shirou was sad as he realized that Kiritsugu's house was destroyed now.  
"Ah. I forgot. Illya, can we stay at your place?"  
Illya nodded.  
"Of course! I have lots of money that you can use to rebuild our dad's house, too, baby brother!"  
"And of course, I can be of help as well, Master." Caster said.  
Shirou looked at Caster. What was once his most fearsome enemy was now his Servant again.  
"Ah, don't call me that. It's just Shirou."  
The three of them returned to the Einzbern mansion minutes ahead of the police, who came and examined the destroyed Fuyuki church and would do so for months before concluding there was no evidence. They would blame the incident on a gas leak. 

Several months had passed, and Shirou, Taiga and Mediatria were living together in the same reconstructed Fuyuki household.  
Taiga, while not exactly happy with what happened to Sakura, came to appreciate Mediatria's appearance in the home.  
Shirou had never found a way to undo the absorption that Caster had wrought. But Mediatria was helpful and doted on Shirou (more than he thought necessary).  
Deep in Mediatria's heart, there had been a permanent change enacted. She no longer sought more power and satisfied her one life goal- being happy.  
She worked on models, helped Shirou in the kitchen, and was content with her life.   
She smiled as she saw him off for school one morning. Taiga left shortly behind him, once again demonstrating her capabilities as a teacher by arriving after the student.  
As Mediatria smiled, she realized this was a true victory.


End file.
